Spotted a bug on this. If you go back or forward in your browser to a blog post, it just shows a bunch of JSON code. You have to reload to get the site to properly show.
Could be changed to only preventDefault/stopPropagation if it doesn't match one of the specially tagged links, or by setting up a different selector for the specially handled links.
Thanks for taking care of this! I like what you're doing with this. As a Tumblr-head, I think you should also consider adding follow, like and reblog functionality. The API also has functions for this.